🐛 Refresh stale server address in registered runners 🐛

Runners registered when the container IP was the default kept that IP
in their .runner file. After a restart the IP pointed elsewhere, so
every Declare call timed out and no runner could connect. The address
is now rewritten to the current server address on each start.

- rootfs/usr/local/bin/start-runners: update the address field of an existing .runner to SERVER_ADDRESS when it differs, logging each change
- TODO.AI.md: record the cause, the fix and its verification

rootfs/usr/local/bin/start-runners

@@ -151,6 +151,12 @@ __register_runner() {
 			return 1
 		fi
 	fi
+	# .runner stores the server address from registration; a container IP baked in earlier goes stale
+	# after a restart, so point it at the current SERVER_ADDRESS every start
+	if [ -f "$runner_dir/.runner" ] && ! grep -q -F -- "\"address\": \"$SERVER_ADDRESS\"" "$runner_dir/.runner"; then
+		__log "Updating $runner_name server address to $SERVER_ADDRESS"
+		sed -i "s|\"address\": *\"[^\"]*\"|\"address\": \"$SERVER_ADDRESS\"|" "$runner_dir/.runner"
+	fi
 	__log "Runner $runner_name registered"
 }
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